Regression introduced in MPIOSupportedDeviceList registry value due to Windows Server 2012 update rollup 2779768

Applies to: Windows Server 2012 StandardWindows Server 2012 StandardWindows Server 2012 Datacenter More

Symptoms


Consider the following scenario:

  • You have a system running Windows Server 2012.
  • You have update rollup KB 2779768 installed.
  • You install a third party Device Specific Module (DSM) on Windows Server 2012.
With the update rollup KB 2779768 installed, the registry values for MPIOSupportedDeviceList in an DSM's INF file are not registered correctly. As a result, the disk devices that were not registered end up not being supported by the DSM.

The DSM is required for Windows Server 2012 to work correctly with third party storage and use its Multi-path Input/output (MPIO) capabilities. 

If the DSM is installed after installing update rollup KB 2779768, the registry value MPIOSupportedDeviceList indicates only one device string:

Path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MPDEV
Type: MULTI_SZ
Value: MPIOSupportedDeviceList

Cause


This issue has been caused by a regression introduced by the update rollup KB 2779768 in Windows Server 2012. There was a problem processing Multi-String registry values due to the regression.

The installed DSM is capable of supporting multiple storage types and populates the registry value MPIOSupportedDeviceList as per entries in its DSM driver's inf file. The list of string values provided in the registry value MPIOSupportedDeviceList indicate the different storage devices supported by the same DSM MPIO driver.

Resolution


The issue has been fixed in the April 2013 update rollup for Windows Server 2012:

http://support.microsoft.com/kb/2822241